U.S. Pat. No. 5,326,652 describes such an accumulator and its housing. However, in that document, the problem of the internal pressure of the accumulator is not mentioned. In fact, accumulators create pressures inside enclosures formed by housings containing them. This pressure may sometimes be so large that the enclosure explodes, especially if the accumulator is of the type containing lithium. Valves may then be provided which open when the pressure exceeds a certain value that is incompatible with the rigidness of this enclosure. When the enclosure pressure increases, a band at a tightening part of the valve may protrude from the walls of the housing of the container. However, once the internal or container gas pressure returns to its normal value, it is possible that the protruding band does not return to its initial position. Another problem is preventing outside air from entering the housing, thereby contaminating the battery elements, when the internal pressure is less than the external pressure.